The prior art discloses wheelchair systems that can climb stairs and curbs, although not with ease or necessarily in a safe manner that protects against the wheelchair slipping out of control down the stairs.
For example, U.S. patent Ser. No. 7,850,189 that issued Dec. 14, 2010 to Barber et al. discloses a curb climbing wheelchair system having left and right-side attachments that are designed to be attached to the left and right-side portions, respectively, of a standard wheelchair to enable a wheelchair occupant to climb a curb, bump or other obstruction without the aid of another individual. Each attachment includes a ramp extending from a telescoping arm that is designed to be attached, via a clamping system, to one side of the wheelchair. When not in use, the ramps are folded and stowed away on the sides of the wheelchair. During use, the ends of the ramps are placed on the curb to allow the wheelchair occupant to climb the curb. To retrieve the ramps, the wheelchair occupant moves the telescoping arms, if necessary with the aid of an attached circular handle, to lift the ramps thus allowing the wheelchair occupant to grab the ramps. The retrieved ramps then are stowed away until needed. Unfortunately, with this wheelchair design it is physically demanding and time consuming for the wheelchair occupant to setup and store the ramps whenever they run into an obstacle. It also appears that the wheelchair ramps cannot be used with a flight of stairs, and it limited to overcoming curbs and other small obstacles.
Additionally, U.S. patent Ser. No. 4,556,229 that issued Dec. 3, 1985 to Bihler discloses an apparatus comprising rotating flat tracks that is attached to the bottom of a wheelchair for moving the wheelchair on a flight of steps like a conveyor belt. The apparatus has a support adapted to engage underneath the wheelchair when it is in upright condition. Two or more tracks allow the wheelchair to move over uneven terrain and up and down stairs. A safety device is connected to a latch for blocking the latch from moving into the freeing position when the tracks are inclined at more than a predetermined angle to the horizontal. Thus, the wheelchair cannot be released from the support-tracks when it is moving on an incline. Never-the-less, the apparatus must be deployed every time the wheelchair faces an obstacle, but the apparatus is not easily stored or deployed from the wheelchair.
An object of the present invention is to solve these problems by providing a wheelchair that can be pulled up a flight of stairs, or over obstacles, by a caregiver pulling on the back of the chair, and thus not require a second helper lifting the front of the wheelchair; nor does it require the deployment of ramps or similar apparatuses; and it comprises a safety mechanism to prevent the wheelchair from rolling down the stairs if the caregiver loses control.